Positioning systems have historically been based upon many different technologies, but always have been used exclusively to determine the location of the user. Throughout history, ship captains and cross country explorers determined their direction of travel using the sun, stars, and geophysical features. Further invention and development improved upon the sophistication and accuracy of positioning aids. Mechanical devices such as the compass for direction finding were developed. The sextant was a significant improvement for location determination at sea. The age of electronics has provided radio positioning apparatus to better and more reliably determine a user's location. OMEGA, VOR, RADAR, TACAN, TRANSIT, LORAN, and recently the Global Positioning System (GPS) have achieved ever increasing accuracy in positioning.
All of the above modern positioning devices, or systems, share a common deficiency. The systems determine the location of those using them and provide no further function. The most accurate positioning technology available today, GPS, can pinpoint a user to within a few meters anywhere on the face of the earth, but only the GPS user knows this location information. Frequently, what is needed is for someone else, at another site, to know the precise location of the positioning system's user. For example, if the location of an automobile accident is only known by those at a crash site, how does an emergency medical technician helicopter know where to go to aid the victim? What is needed is an apparatus for reporting accurate GPS location of an unknown site to other locations involved in an application.
Some positioning scenarios require the location of an unmanned remote site to be reported to a manned location for monitoring and/or management of future action. In such an example, the remote site may be uninhabitable for some environmental reason (as at the edge of an active volcano), thereby prohibiting a user from operating the GPS positioning system and reporting the user's location. Such critical data may be needed to predict where to evacuate people in endangered areas based upon location. What is needed is to know the remote site's location at a second location.
Similar positioning systems needs occur in search and rescue operations. For example, an automatic emergency GPS positioning system operating on a sinking vessel with unconscious people aboard is of little use unless the location of the vessel can be delivered to a rescue party. Precious time can be lost before a person may be able to communicate the vessel's location. A method to automatically transmit the location data would be invaluable.
The above examples are representative of the myriad of possible applications of an apparatus to facilitate the transmission of GPS location data from an unknown location to another control, monitor, or action site or multiple sites. Since a constraint on such a transmission is the environment separating the sites, a variety of methods and apparatus are required to satisfy all the constraints. The apparatus used to connect the GPS positioning system must be capable of interfacing with a variety of communications equipment, singly or in combination, to achieve operating flexibility with any communications hardware having common interface characteristics.